Home
Class 12
PHYSICS
When a light of frequency 9 xx 10^(14)...

When a light of frequency `9 xx 10^(14) Hz` is incident on a metal surface, photoelectrons are emitted with a maximum speed of `8 xx 10^(5) ms^(-1)` . Determine the threshold frequency of the surface.

Text Solution

Verified by Experts

Given data `:`
The frequency of the incident light `v = 9 xx 10^(14) Hz`
Maximum speed of photo electrons ` V _("max") = 8 xx 10^(5) ms^(-1)`
To Find `:`
Threshold frequency of the surface `v_(0) = ?`
Mass of the electron `m = 9.1 xx 10^(-31) kg `
According to Einstein's photo electrons equation `hv = hv_(0)+ ( 1)/(2) mv_("max")^(2)` Planks constant `h = 6.6 25 xx 10^(-34 )Js`.
`hv = (1)/(2) mv_("max")^(2) = hv_(0)`
`v_(0) = v- ( mv_("max")^(2))/( 2h)`
`= ( 9 xx 10^(14)) - ( ( 9.1 xx 10^(-31) xx 8 xx 10^(5) xx 8 xx 10^(5))/( 2 xx 6.626 xx 10^(-34)))`
` = ( 9 xx 10^(14)) - ( ( 582.4 xx 10^(13))/( 13.252))`
`= ( 9 xx 10^(14)) - ( 4.394 xx 10^(14))`
`v_(0) = 4.606 xx 10^(14) Hz`
Promotional Banner

Similar Questions

Explore conceptually related problems

Light of frequency 7.21xx10^(14)Hz is incident on a metal surface. Electrons with a maximum speed of 6.0 xx 10^(5) m/s are ejected from the surface. What is the threshold frequency for photoemission of electrons?

The work function of caesium metal is 2.14 eV. When light of frequency 6xx10^(14)Hz is incident on the metal surface, photoemission of electrons occurs. What is the a. maximum kinetic energy of the emitted electrons, b. stopping potential, and c. maximum speed of the emitted photoelectrons ?

The work function of a metal is 6.6 xx 10^(-14) J . Find its threshold frequency.

Speed of light in glass is 2xx 10^(8) ms^(-1) . Find the refractive index of glass.

The work function of a metal is 6.626 xx 10^(-19) J. The threshold frequency is

If the velocity of light in a medium is 2.25 xx 10^(8) ms^(-1) then the refractive index of the medium will be

Monochromatic light of frequency 6 xx 10^(14) Hz is produced by a laser. The power emitted is 2.0 xx 10^(-3) W . How many photons per second on an average are emitted by the source ?